Re: CAPTCHA image validation in web form

[Nathan Andelin <nandelin@xxxxxxxxx>]

> From: Walden H. Leverich
> I guess you could do stuff like "What's the
> third word of the fourth paragraph on this page".

That's kind of what I was thinking.  A Captcha is a low fence that humans can generally cross but automated bots have a hard time with.

The article that Mike referred to pointed out that bots are generally thwarted by CSS and JavaScript injection.  And similar to distorting an image, it seems that various techniques could be used to seemingly randomize and distort injected CSS and JavaScript that would make it hard for bot authors to figure out your algorithm.

If it gets to the point that hackers continually modify their bots to get around your algorithms, and post malicious or nuisance content to your database, then it may be time to supply all users with credentials and authenticate against them.

Captcha is a low fence; something in between open forms and authenticated input.

Nathan.